Tacky mat stack

ABSTRACT

An improved tacky mat stack is comprised of a plurality of superimposed tacky mat sheets each having a composite laminar construction consisting of a thin flexible support film forming an adhesive barrier surface on the bottom of the sheet, a reinforcing fibrous web coextensive with the support film and firmly secured thereto and a pressure-sensitive adhesive coating carried by the film, the adhesive coating being in secure engagement with the reinforcing fibrous web and forming a tread surface of the sheet. A corner pull tab extending to the edge of each sheet provides nonadhering engagement between super-imposed sheets and means for securely gripping the uppermost sheet for stripping it from the stack.

United States Patent Nappi [4 1 May 30, 1972 541 TACKY MAT STACK [72]Inventor: John J. Nappi, 80 Berkley Rd., Berlin,

Conn. 06037 [22] Filed: Nov. 19, 1970 [21] Appl.No.: 91,095

Primary Examiner-Leon G. Machlin Attorney-Prutzman, Hayes, Kalb &Chilton [5 7] ABSTRACT An improved tacky mat stack is comprised of aplurality of superimposed tacky mat sheets each having a compositelaminar construction consisting of a thin flexible support film formingan adhesive barrier surface on the bottom of the sheet, a reinforcingfibrous web coextensive with the support film and firmly secured theretoand a pressure-sensitive adhesive coating carried by the film, theadhesive coating being in secure engagement with the reinforcing fibrousweb and forming a tread surface of the sheet. A corner pull tabextending to the edge of each sheet provides nonadhering engagementbetween super-imposed sheets and means for securely gripping theuppermost sheet for stripping it from the stack.

12 Claims, 4 Drawing Figures PATENTEDMAYBO I972 3. 665.5 43

INVENTOR JOHN J. NAPPI ATTORNEYS TACIKY MAT STACK BACKGROUND AND SUMMARYOF THE INVENTION The present invention relates generally to a tacky matstack adapted to remove accumulated dirt particles from the underside ofshoes or other traffic during passage thereof across the mat. Moreparticularly, it is directed to a new and improved tacky matconstruction which facilitates the easy sequential removal of eachuppermost mat sheet from the stack.

A tacky mat stack of the type involved in this invention has beendescribed in detail in my earlier U.S. Pat. No. 3,083,393. Broadly, itconsists of a plurality of superimposed coextensive sheets, each havinga pressure-sensitive adhesive on the top surface thereof. As will beappreciated, the tightly woven fabric or cloth backing of each adhesivesheet necessarily exhibited sufficient strength to be stripped or peeledfrom the stack without tearing or rupturing. Accordingly, a tightlywoven, strong and sturdy fabric has heretofore been used for thispurpose.

Unfortunately, the constant passage of pedestrian traffic across a stackcontaining several adhesive sheets constantly forces the cloth backingof each sheet into intimate engage ment with the adhesive tread surfaceon the adjacent underlying sheet. This disadvantageously causes theadhesive to penetrate the cloth backing, resulting in the tight bondingor welding of the superimposed sheets to each other. This problem isparticularly evident on the lowermost sheets of the stack and createssubstantial difficulty in effecting the desired stripping or peeling ofthe soiled layers from the mat stack.

Accordingly, in my US. Pat. No. 3,501,797 there is described a stackconstruction incorporating a transversely extending pull string at oneend of each sheet for effecting preliminary release of the end portionof the top sheet. As indicated in that patent the pull string is merelyinterposed between adjacent sheets and is not secured thereto. As thestring is pulled from its rest position, it effects a sweeping motion toproduce the desired initial releasing action. However, this constructiondoes not reduce the tendency of the sheets to adhesively weld to oneanother. Additionally, the sheets of the mat stack are not provided withmeans for securely gripping the individual sheets themselves, and unlessgreat care is taken to ensure the continued separation of thestring-released sheet portion, it will readily reengage the underlyingsheet and due to its tacky nature will immediately adhere theretocausing substantial difficulty in effecting the desired separation.

Attempts to insert conventional release layers, such as a layer ofsilicone treated paper or the like, between the tacky mat sheets of thestack in order to prevent the undesirable bonding or welding of thesesuper-imposed sheets has proved unsatisfactory. Such release layersdisadvantageously permit sliding and other movement of the sheetsrelative to each other, thereby creating a safety hazard for the user ofthe mat and unwanted adhesion of the top mat sheet to the pedestriantraffic using the mat.

Accordingly, it is a primary object of the present invention to providea new and improved tacky mat stack of pressuresensitive adhesive coatedsheets exhibiting ease of separation, coupled with relative immovabilitybetween the sheets of the stack during use.

Another object of the present invention is to provide a tacky mat stackof the type described wherein the adhesive sheets are composite laminarstructures incorporating an adhesive barrier suited for releasableadherence to the underlying tread surface while preventing penetrationtherethrough by the adhesive, thereby preventing the disadvantageouswelding of the sheets and facilitating rapid separation thereof despitethe passage of heavy traffic loads over the mat stack.

Still another object of the present invention is to provide a tacky matstack of the type described comprised of new and improved compositeadhesive sheets incorporating materials that independently might notexhibit the requisite strength characteristics but when combined providean extremely strong and durable structural relationship in a highlyefficient and economical manner without disadvantageously increasing thethickness of the adhesive sheet structure.

A further object of the present invention is to provide a tacky matstack of the type described having an improved easily grasped pull tabfor effecting an adhesive-free area between the sheets and initialseparation of the sheets in the stack.

Other objects will be in part obvious and in part pointed out in moredetail hereinafter.

These and related objects are accomplished in accordance with thepresent invention by providing a new and improved tacky mat comprised ofa plurality of super-imposed tacky mat sheets each having a compositelaminar construction. The sheets consist of a thin, highly flexiblesupport film forming an adhesive barrier surface on the underside of thesheet, a reinforcing fibrous web coextensive with the support film andfirmly secured thereto and a pressure-sensitive adhesive coating carriedby the support film, the adhesive coating being in secure engagementwith the reinforcing fibrous web. The adhesive coating penetrates andembeds the fibrous web therein and assures unified cooperative actionbetween the supporting film and the reinforcing web.

A better understanding of the objects, advantages, features, propertiesand relationships of the invention will be obtained from the followingdetailed description and the accompanying drawing which set forth anillustrative embodiment indicative of the way in which the principles ofthe invention are employed.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a perspective view of an embodiment of the tacky mat stack ofthe present invention mounted within a suitable frame;

FIG. 2 is an exploded perspective view of the tacky mat stack of FIG. 1with a portion of the frame broken away and some of the mat sheetsarranged to show both their top and bottom surfaces;

FIG. 3 is an enlarged sectional view taken along the line 3- 3 of FIG. 2illustrating the composite laminar construction of a single mat sheet;and

FIG. 4 is an enlarged perspective view of the improved pull tab portionof the tacky mat stack illustrating the ease with which an overlyingadhesive sheet can be removed from the stack.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing ingreater detail wherein like reference numerals indicate like partsthroughout the several figures, a tacky mat assembly 10 is illustratedas being comprised of a generally rectangular mat stack 12 of flatsuperimposed adhesive sheet material securely mounted within anappropriate frame member 14. Although the particular frame used with thestack may be of the type described in greater detail in my earlier US.Pat. No. 3,083,393, the illustrated frame 14 is of a type having a flatbase 16 to which the stack 12 is directly adhered and from which it issubsequently stripped. The frame may be made of any suitable material,such as aluminum.

The assembly 10 including the stack 12 of pressure-sensitive adhesivesheets is usually located within a pedestrian traffic passageway and isparticularly useful in the industrial field where delicate or dust-freemanufacturing operations or techniques are performed or whereenvironmental control is essential, such as in clean rooms and the like.It will, of course, be appreciated that the tacky mat stack of thepresent invention also has beneficial hospital uses, as at the entry tooperating rooms or other areas wherein control of dust particles isdesired.

As described in my aforementioned patents, the stack may be mounted on aflat, generally rectangular base member, such as a masonite board havingdimensions slightly greater than the adhesive sheets carried thereby.However, as illustrated in FIG. 2, the stack 12 of the present inventionis advantageously applied directly to the base 16 of the frame 14 andfully removed therefrom in a sequential manner after use of eachuppermost sheet.

The lowermost adhesive sheet 18 of the stack 12 is generally of the typedescribed in my earlier patents in that it is double faced with adhesivewhile the remaining or overlying sheets 20 are substantially identical,have adhesive on only the tread surface thereof and incorporate thecomposite laminar sheet construction of the present invention. Thebottom surface 24 of lowermost sheet 18 is provided with a full coatingof highly tacky adhesive for securely attaching that sheet to the base16 of the frame. As will be appreciated, the adhesive on the surface 24preferably possesses greater bonding or adhering power than the adhesiveon the top or tread surface 26 of sheet 18 in order to assure firmattachment of the stack to the frame when the superimposed sheets arepeeled from the stack.

As mentioned, each of the overlying sheets 20, usually about nine innumber, are substantially identical. Accordingly, for ease ofillustration and clarity of understanding only one such sheet structurewill be described in detail. Unlike the adhesive coated heavy clothsheets described in my aforementioned patents, the pressure-sensitiveadhesive coated sheets 20 of the present invention are composite laminarstructures which rely to some degree upon the cooperative and coactingreinforcement of the different components of the structure to providethe desired strength characteristics thereof.

Referring specifically to FIG. 3, each composite adhesive sheetstructure 20 is comprised essentially of a thin pliable support film 30on which rests a fibrous reinforcing web material 32 of gauze-like openweave embedded within a coating 34 of adhesive. In the preferredembodiment illustrated, the adhesive coating 34 extends through thegauze web 32 so as to contact and securely adhere to the support film30. This effects not only an anchoring or bonding of the gauze-likematerial to the support but also provides operating unity and integritybetween the components of the composite laminar structure. That is, eachcomponent of the structure cooperates with the other components tostructurally reinforce the sheet.

It will be appreciated that a single layer of gauze-like fabric has onlya low degree of tear strength and may readily rip when subjected to aforce such as that encountered during sheet separation from the stack.Such low strength material with its open weave would not ordinarily besuited for use as a replacement for the cloth backing used heretofore.By the same token, a thin pliable film of high flexibility and finegauge is also susceptible to easy rupture and tear. However, inaccordance with the present invention the adhesive combination of theweak open-weave gauze-like fabric and the thin pliable film causescooperative reinforcement of each structural component and mutualreinforcement thereof.

The film 30 utilized as a base or support in the composite laminarstructure of the present invention is preferably a thin flexible memberhaving a smooth, fiat, exposed bottom surface 36 that will releasablyadhere to the pressure-sensitive adhesive of an underlying sheet yet beimpermeable thereto. Thus, the film forms a continuous or uninterruptedbarrier which prevents flow of the adhesive therethrough from eitherabove or below the film despite its thin gauge and susceptibility totearing. The film found to give good results is generally of a thicknessno greater than about 0.010 inch and usually of 0.005 inch and less inthickness. Plastic films, such as films of vinyl polymers and copolymersas well as polyethylene and similar materials, possess these desiredcharacteristics. Additionally, the plastic films do not tend to dry upand become brittle with age and exhibit good elongation, pliability andflexibility characteristics coupled with the ability to releasablyadhere to the confronting pressure-sensitive adhesive coating of anadjacent underlying sheet. It will, of course, be appreciated that theexcellent chemical resistance of such films does not prevent the securebonding of the open gauze-like fabric to the film by the adhesivecoating 34 applied to the top surface thereof.

The fibrous web material 32 embedded within the pressuresensitiveadhesive coating 34 and secured to the plastic film thereby ispreferably a gauze-like fabric of open-weave construction. However,similar highly porous fibrous structures such as scrims or othernonwoven webs could be utilized in accordance with the present inventionto cooperate with the plastic films and provide the desired reinforcedstrength characteristics needed in the composite sheet.

The particular pressure-sensitive adhesive coating utilized to form thetread surface 38 of each sheet 20 and adhere the web 32 to the film 30in accordance with the present invention should be of moderatetackiness. It is also necessary that the pressure-sensitive adhesivecomposition be of the type which retains its tackiness over an extendedperiod of time. Such material is generally of the type found in maskingtape and, in essence, is substantially the same as that described in myearlier US. Pat. No. 3,083,393.

An added feature of the present invention is the utilization of pulltabs 42 on one corner of each adhesive surface of the sheets tofacilitate stripping of each uppermost sheet from the remainder of thetacky mat stack. In the preferred embodi ment illustrated, this takesthe form of a small generally rectangular piece of nontacky material,such as a tough, dimensionally stable polyester film, e. g., Mylar" soldby E. l. du Pont de Nemours, of about 1 mil thickness in firm adhesivecontact with the tread surface 38 of each composite sheet structure. Thetab 42 is provided with a leaf portion 44 extending beyond the edge ofthe adhesive sheet and folded back to facilitate easy grasp thereof bythose persons responsible for stripping the uppermost sheet from the matstack. The remainder of the tab, which may contain identifying indiciasuch as a trademark or the like, is securely fastened to the adhesivesheet and, as will be appreciated, is in confronting relationship withthe plastic film on the undersurface of a superimposed sheet so thatthere is plastic-to-plastic nonadhesive contact therebetween at onecomer of each sheet.

The bottom sheet 18 of the stack 12 also is provided with a tab 42 onboth adhesive surfaces to assure the presence of an initial strippingarea free of adhesive between the sheet 18 and base plate 16 of theframe. Thus, it is quite easy for the operator to merely grasp thefolded leaf portion 44 of the exposed tab 42 and lift the uppermostsheet from the underlying member in the area where there is nointervening adhesion. As shown, the tab 42 is of sufficient size toprovide a good gripping area and permit continued peeling of thesuperimposed sheet structure from the stack.

As will be apparent to persons skilled in the art, variousmodifications, adaptations and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

I claim:

1. In a tacky mat stack suited for the passage of pedestrian trafficthereacross and the concurrent adhesive removal of dirt particles fromsaid traffic by the tread surface on the uppermost sheet of said stack,the improvement in a plurality of superimposed tacky mat sheets ofcomposite laminar construction wherein each superimposed sheet iscomprised of a flexible support film having an integraladhesive-impermeable barrier surface extending across essentially thefull underside thereof, a reinforcing fibrous web coextensive with saidflexible support film and secured to the top side thereof; and apressure-sensitive adhesive coating carried by the top side of saidsupport film and forming an upwardly facing pressuresensitive adhesivetread surface of the sheet, said coating being in secure penetratingengagement with said reinforcing fibrous web and in nondelaminatingengagement with said support film to provide said composite laminarstructure, said barrier surface being effective to prevent penetrationtherethrough of the adhesive tread carried by an underlying sheet andconsequent adhesive welding of superimposed sheets during the passage ofpedestrian traffic across the stack,

said barrier surface facilitating easy separation of each topmost sheetafter passage of pedestrian traffic thereon while preventing inadvertentrelative movement between the superimposed sheets of the stack.

2. The tacky mat stack of claim 1 wherein the flexible support film is athin solid plastic sheet carrying both the reinforcing'fibrous web andthe adhesive coating, the barrier surface of said film being disposed inoverlying confronting relationship with the pressure-sensitive adhesiveof an underlying sheet and being releasably held thereby to preventrelative movement therebetween while facilitating peelable separationtherefrom.

3. The mat stack of claim 2 wherein the film of plastic has a thicknessless than 0.01 inch.

4. The mat stack of claim 1 wherein the fibrous web exhibits an open,gauze-like network facilitating penetration of the adhesive coatingtherethrough into secure engagement with the support film.

5. The mat stack of claim 1 wherein the fibrous web is embedded in thepressure-sensitive adhesive coating and secured to the film by saidcoating 6. The mat stack of claim 1 wherein a portion of the treadsurface is provided with a gripping member engaging one edge of thesheet, said member being in confronting relationship with the barriersurface of an overlying sheet to provide constant nonadhering contacttherebetween at said one edge while facilitating initial separation ofthe overlying sheet from the stack.

7. In a tacky mat stack suited for the passage of pedestrian trafficthereacross and the concurrent adhesive removal of dirt particles fromsaid traffic by the tread surface on the uppermost sheet of said stack,the improvement in a plurality of superimposed tacky mat sheets havingupwardly facing tread surfaces wherein a portion of the upwardly facingtread surface of each sheet is provided with a pull tab having agripping portion extending freely from the sheet, each overlying sheetbeing provided with an integral non-delaminating adhesive barrierextending across essentially the full sheet in confronting arrangementwith the upwardly facing adhesive tread surface of the underlying sheetand with said pull tab, said tab extending from the edge of the sheetand cooperating with said confronting barrier to provide constantnonadhesive contact between superimposed sheets at said edge portion,said gripping portion being interposed between the pull tab and thebarrier for exposure upon removal of the overlying sheet.

8. The tacky mat stack of claim 7 wherein the sheets are generallyrectangular planar members and the pull tab is a plastic film of hightear strength positioned at one corner thereof to prevent adhesionbetween adjacent sheets at said one comer.

9. The mat stack of claim 7 wherein the pull tab is a polyester film ofabout 1 mil thickness.

10. In a tacky mat stack suited for the passage of pedestrian trafficthereacross and the concurrent adhesive removal of dirt particles fromsaid traffic by the tread surface on the uppermost sheet of said stack,the improvement in a plurality of superimposed tackymat sheets ofcomposite laminar construction wherein each superimposed sheet iscomprised of a flexible support film having an integraladhesive-impermeable barrier surface extending across essentially thefull underside thereof and a pressure-sensitive adhesive coating carriedon the top side of said support film and forming an upwardly facingpressure-sensitive adhesive tread surface of the sheet, said coatingbeing in secure non-delaminating engagement with said support film toprovide said composite laminar structure, said barrier surfacepreventing penetration therethrough of the adhesive tread carried by anunderlying sheet and consequent adhesive welding of superimposed sheetsduring the passage of pedestrian traffic across the stack, said barriersurface facilitating easy separation of each topmost sheet after passageof pedestrian traffic thereon while preventing inadvertent relativemovement between the superimposed sheets of the stack.

11. The tacky mat stack of claim 10 wherein the flexible support film isa thin solid plastic sheet and the barrier surface of said film isdisposed in overlying confronting relationship with thepressure-sensitive adhesive of an underlying sheet and is releasablyheld thereby to prevent relative movement therebetween whilefacilitating peelable separation thereof.

12. The mat stack of claim 10 wherein one edge of the sheet is providedwith gripping means in confronting relationship with the barrier surfaceof an overlying sheet to provide constant nonadhering contacttherebetween at said one edge while facilitating initial separation ofthe overlying sheet from the stack.

2. The tacky mat stack of claim 1 wherein the flexible support film is athin solid plastic sheet carrying both the reinforcing fibrous web andthe adhesive coating, the barrier surface of said film being disposed inoverlying confronting relationship with the pressure-sensitive adhesiveof an underlying sheet and being releasably held thereby to preventrelative movement therebetween while facilitating peelable separationtherefrom.
 3. The mat stack of claim 2 wherein the film of plastic has athickness less than 0.01 inch.
 4. The mat stack of claim 1 wherein thefibrous web exhibits an open, gauze-like network facilitatingpenetration of the adhesive coating therethrough into secure engagementwith the support film.
 5. The mat stack of claim 1 wherein the fibrousweb is embedded in the pressure-sensitive adhesive coating and securedto the film by said coating.
 6. The mat stack of claim 1 wherein aportion of the tread surface is provided with a gripping member engagingone edge of the sheet, said member being in confronting relationshipwith the barrier surface of an overlying sheet to provide constantnonadhering contact therebetween at said one edge while facilitatinginitial separation of the overlying sheet from the stack.
 7. In a tackymat stack suited for the passage of pedestrian traffic thereacross andthe concurrent adhesive removal of dirt particles from said traffic bythe tread surface on the uppermost sheet of said stack, the improvementin a plurality of superimposed tacky mat sheets having upwardly facingtread surfaces wherein a portion of the upwardly facing tread surface ofeach sheet is provided with a pull tab having a gripping portionextending freely from the sheet, each overlying sheet being providedwith an integral non-delaminating adhesive barrier extending acrossessentially the full sheet in confronting arrangement with the upwardlyfacing adhesive tread surface of the underlying sheet and with said pulltab, said tab extending from the edge of the sheet and cooperating withsaid confronting barrier to provide constant nonadhesive contAct betweensuperimposed sheets at said edge portion, said gripping portion beinginterposed between the pull tab and the barrier for exposure uponremoval of the overlying sheet.
 8. The tacky mat stack of claim 7wherein the sheets are generally rectangular planar members and the pulltab is a plastic film of high tear strength positioned at one cornerthereof to prevent adhesion between adjacent sheets at said one corner.9. The mat stack of claim 7 wherein the pull tab is a polyester film ofabout 1 mil thickness.
 10. In a tacky mat stack suited for the passageof pedestrian traffic thereacross and the concurrent adhesive removal ofdirt particles from said traffic by the tread surface on the uppermostsheet of said stack, the improvement in a plurality of superimposedtacky mat sheets of composite laminar construction wherein eachsuperimposed sheet is comprised of a flexible support film having anintegral adhesive-impermeable barrier surface extending acrossessentially the full underside thereof and a pressure-sensitive adhesivecoating carried on the top side of said support film and forming anupwardly facing pressure-sensitive adhesive tread surface of the sheet,said coating being in secure non-delaminating engagement with saidsupport film to provide said composite laminar structure, said barriersurface preventing penetration therethrough of the adhesive treadcarried by an underlying sheet and consequent adhesive welding ofsuperimposed sheets during the passage of pedestrian traffic across thestack, said barrier surface facilitating easy separation of each topmostsheet after passage of pedestrian traffic thereon while preventinginadvertent relative movement between the superimposed sheets of thestack.
 11. The tacky mat stack of claim 10 wherein the flexible supportfilm is a thin solid plastic sheet and the barrier surface of said filmis disposed in overlying confronting relationship with thepressure-sensitive adhesive of an underlying sheet and is releasablyheld thereby to prevent relative movement therebetween whilefacilitating peelable separation thereof.
 12. The mat stack of claim 10wherein one edge of the sheet is provided with gripping means inconfronting relationship with the barrier surface of an overlying sheetto provide constant nonadhering contact therebetween at said one edgewhile facilitating initial separation of the overlying sheet from thestack.